For antenna arrangments comprising a plurality antenna elements, for example array antenna systems, it is in many cases important to know which antenna ports actually are connected to which feeder ports, i.e. to which radio chains. This means not only the way they should have been connected, but the way they actually have been connected. It is of most importance that they are connected in a specific desired manner, which means that there is a need to exactly know which radio chain (feeder port) that is connected to which antenna port, or the connection order, presuming the antenna ports are arranged in a given order. An example when this is important is when there is an antenna part for which all antenna elements, or subgroups of antenna elements, are located in such a manner that the radio channel becomes significantly correlated. In one specific example the antenna part comprises a uniform linear array (ULA) intended to be used for sector covering transmission, which means that the beam pattern simultaneously shall cover the entire sector. Such a beam pattern can be generated by the application of a weight vector with phase and/or amplitude taper. Then it is exceedingly important that the individual weights are applied to the intended or the appropriate antenna elements since otherwise the beam pattern will be distorted.
For generating a beam pattern with a desired shape by means of applying a weight vector to an antenna arrangement, or an array antenna, i.e. beamforming, coherency is considered significant in order to enable that the desired beam shape be obtained. This particularly means that the phase and the amplitude in all radio branches must be known with a sufficient accuracy. If the feeder ports are incorrectly connected to the antenna ports, i.e. if radio paths are incorrectly connected to the antenna ports, the beam pattern will be distorted even if phase and amplitude relations are correct or as desired. This means that coherency can be seen as involving, in addition to phase, amplitude and time relations, also spatial locations.
In known arrangements mainly manual methods have been employed to ensure that cables are connected in the appropriate manner, i.e. that the feeder ports are connected to the antenna ports the way they should have been. A simple manual method consists in marking the cables at both ends. However, in practice cables are often connected incorrectly even if the cables have been marked. One reason for this is that there may be many feeder cables. Another reason is that configuration as well as reconfiguration or reconnection of cables often takes place quite far away from the antenna. A physical verification of the cabling is also difficult and time consuming considering that the antennas often are located in high masts. It is extremely difficult to determine if a connection has been established correctly and it is also complicated to handle connection errors since it is difficult to identify how the cables actually have been connected or what the errors are.